*{
    padding:0;
    margin:0;
}
#app{
    position: relative;
    width:600px;
    height: 400px;
    border:2px dashed green;
    margin:20px auto;
}
#timed{
    position: absolute;
    font-size: 20px;
    top:20px;
    left:20px;
}
#score{
    position: absolute;
    top:20px;
    right: 20px;
    font-size: 20px;
}
#main{
    font-size: 100px;
    text-align: center;
    line-height: 300px;
}
p{
    position: absolute;
    text-align: center;
    width: 100%;
    bottom: 120px;
    font-size:16px;
}
ul{
    list-style: none;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 40px;
    line-height: 50px;
}
li{
    margin:0 20px;
}
.mask{
    position: absolute;
    width:100%;
    height:100%;
    top:0;
    left:0;
    background: rgba(1,1,1,0.8);
    display: flex;
    align-items: center;
    justify-content: center;
}
.start{
    width:100px;
    height:100px;
    font-size:18px;
    color:pink;
    background: gray;
    border:none;
}
.start:hover{
    background: red;
    cursor:pointer;
}